The present application relates generally to an optical scanning system. More particularly, the invention provides a synchronously sweeping image based line scanner with coplanar illumination.
Package monitoring capability is a vital task in modern shipping and inventory control systems. To aid in this task, automated scanning systems have been developed. Due to their simplicity and speed, linear image based scanners (also called line scanners) are used for a large variety of scanning tasks. However, they have inherent limitations which affect their overall efficiency and usefulness in certain applications. One primary limitation of linear image based scanners is the inability to simultaneously focus on objects of varying height as the objects move down a transport path in a non-singulated package flow arrangement. Sufficient depth of field for many types of current scanning systems is also a limitation. Although scanning systems do exist having a sufficient depth of field, these systems are often very costly.
There is a need to provide a scanning system which will quickly and efficiently scan objects of differing heights as they travel down a material handling path in a non-singulated flow pattern. There is a still further need to provide a scanning system which is cost efficient to manufacture.
The invention comprises a system for scanning human or machine readable information located on objects moving in a transport direction along a transport path. The system includes an imaging device having a first observation path. A scanning zone is located along the transport path. A sweeping unit is positioned to receive light from the scanning zone along a second observation path and to reflect the light along the first observation path to the imaging device. The sweeping unit moves in a manner so that the second observation path is moved across the scanning zone along a sweep path. The imaging device captures a plurality of image segments that extend generally across the transport path. Movement of the sweeping unit is preferably synchronized to movement of the objects along the transport path.
In another respect, the invention comprises a system for scanning human or machine readable information located on objects moving in a transport direction along a transport path. The system includes a profiling device that provides a height profile of the objects moving along the transport path. The system also includes an imaging device having a first observation path and an automatic focusing system. A controller is in communication with the profiling device to receive the height profile. A scanning zone is located along the transport path. The system further includes a sweeping unit that is positioned to receive light from the scanning zone along a second observation axis and to reflect the light along the first observation path to the imaging device. The sweeping unit moves in a manner so that the second observation path is moved through the scanning zone along a sweep path, during which time the imaging device captures a plurality of image segments that extend generally across the transport path. The controller signals the focusing system to adjust the focusing system and optionally zoom as the sweeping unit moves along the sweep path in accordance with the object height profile.
In another aspect, the invention comprises a method of scanning human or machine readable information located on objects. The objects are preferably moving along a transport path in a single direction. Image data is collected from successive sweeps along a sweep path. Each sweep comprises a plurality of image segments successively spaced across a transport path. The collection of image data includes the steps of imaging 1xe2x88x92N successive image segments across a first sweep path, then imaging 1xe2x88x92N successive image segments across a next sweep path that partially overlaps the first sweep path. The image data is then reviewed to recognize human or machine readable code.